
<template>
  <div>
    <router-link tag='div' to='/' class="header-abs" v-show='showabs'>
      <div class="iconfont header-abs-back">&#xe624;</div>
    </router-link >
    <div class="header-fixed" v-show="!showabs" :style='opacityStyle'>
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>

<script>
export default {
  name:'DetailHeader',
  data(){
    return{
      showabs:true,
      opacityStyle:{
        opacity:0
      }
    }
  },
  methods:{
    handleScroll(){
      const top = document.documentElement.scrollTop;
      if(top > 60){
        let opacity = top / 140;
        opacity = opacity > 1 ? 1 : opacity;
        this.opacityStyle = {
          opacity:opacity
        }
        this.showabs = false;
      }else{
        this.showabs = true;
      }
    }
  },
  mounted(){
    window.addEventListener('scroll',this.handleScroll);
  },
  beforeDestroy(){
    window.removeEventListener('scroll', this.handleScroll)
  }
}
</script>

<style lang="stylus" scoped rel="stylesheet/stylus">
  @import '~styles/varibles.styl'
  .header-abs
    position :absolute;
    left :0.2rem;
    top :0.2rem;
    width :0.8rem;
    height :0.8rem;
    text-align :center;
    line-height :0.8rem;
    border-radius 0.4rem;
    background-color:rgba(0,0,0,0.8);
    .header-abs-back
      color:#fff;
      font-size :0.4rem;
  .header-fixed
    z-index :2;
    position: fixed;
    top: 0;
    left :0;
    right :0;
    height: $headerHeight
    line-height: $headerHeight
    text-align: center
    color: #fff
    background: $bgColor
    font-size: .32rem
    .header-fixed-back
      position: absolute
      top: 0
      left: 0
      width: .64rem
      text-align: center
      font-size: .4rem
      color: #fff
</style>
